Apple, Samsung and Microsoft are among a host of tech companies and carmakers implicated in a new report that sheds light on apparent child labor practices in the sourcing of minerals used to create batteries.

An Amnesty International report — created in partnership with Africa-focused NGO Afrewatch — delves into the world of cobalt mining in the Democratic Republic of the Congo (DC), which accounts for half of the world’s cobalt sourcing, finding that children as young as seven are working in dangerous conditions for a mere dollar or two of income each day.

Beyond allegations of children laboring in between or instead of school, the report claimed that working conditions are extremely hazardous. Aside from the issue of working in cramped conditions daily with little to no protection, Amnesty claimed that some 80 miners died in southern DRC during the final four months of 2015. Many more deaths may have gone unreported since, in the event of an accident, bodies can be buried in the rubble, the organization added.

The report focused on Congo Dongfang Mining (CDM), a DC-based subsidiaries of China’s Huayou Cobalt, which “buys cobalt from [traders in] areas where child labour is rife.” The cobalt is then sold to battery component makers, who use it to develop batteries which are sold on to carmakers and tech companies, the report claimed.

Movement of cobalt from DRC mines to the global market — via Amnesty International

Amnesty said it traced 16 multinational companies who are listed as customers of Huayou Cobalt.

Samsung SDI, the division of the Korean tech giant that deals with batteries, told TechCrunch that has no dealings with either Huayou Cobalt or CDM. It added that it “conducts written evaluations and on-site inspections in areas such as human rights, labor, ethics, environment, and health and safety on a two-year basis and awards them with certification.” Emails to Apple and Microsoft did not elicit responses at the time of writing.

Amnesty itself said it received a mixture of responses from the 16 companies it contacted:

One company admitted the connection, while four were unable to say for certain whether they were buying cobalt from the DRC or Huayou Cobalt. Six said they were investigating the claims. Five denied sourcing cobalt from via Huayou Cobalt, though they are listed as customers in the company documents of battery manufacturers. Two multinationals denied sourcing cobalt from DRC.

“It is a major paradox of the digital era that some of the world’s richest, most innovative companies are able to market incredibly sophisticated devices without being required to show where they source raw materials for their components,” Afrewatch Executive Director Emmanuel Umpula said in a statement.

“The abuses in mines remain out of sight and out of mind because in today’s global marketplace consumers have no idea about the conditions at the mine, factory, and assembly line. We found that traders are buying cobalt without asking questions about how and where it was mined,” Umpala added.

“Amnesty International and Afrewatch are calling on multinational companies who use lithium-ion batteries in their products to conduct human rights due diligence, investigate whether the cobalt is extracted under hazardous conditions or with child labour, and be more transparent about their suppliers,” the two organizations said in a joint statement.

Update: Microsoft provided TechCrunch with the following statement:

Microsoft is fully committed to the responsible sourcing of raw materials used in our products. That is why we work closely with and support organizations like Pact that are focused on addressing human rights issues in mining. We are specifically engaged with them on a pilot project to eradicate child labor in the Katanga region of the Congo related to cobalt mining.

Update: Apple provided TechCrunch with the full text of its statement to Amnesty International — a portion of which appeared in the Amnesty posting. It is reproduced in its entirety below.

We appreciate the concerns Amnesty International raised. As discussed in our recent conversation, we share your interest in and dedication to improving the lives of workers around the world. Apple believes every worker in our supply chain has a right to safe, ethical working conditions.

Underage labor is never tolerated in our supply chain and we are proud to have led the industry in pioneering new safeguards. We not only have strict standards, rigorous audits and industry-leading preventative measures, but we also actively look for any violations. Any supplier found hiring underage workers must 1) fund the worker’s safe return home, 2) fully finance the worker’s education at a school chosen by the worker and his or her family, 3) continue to pay the worker’s wages, and 4) offer the worker a job when he or she reaches the legal age.

We have been reporting on our supply chain for 10 years because we believe transparency and the feedback that comes with it makes us better. Of more than 1.6 million workers covered in 633 audits in 2014, our auditors uncovered 16 cases of underage labor and all were successfully addressed. We take any concerns seriously and investigate every allegation. We engage with our suppliers all over the world, including directly with smelters and refiners. We’re also working on site to support programs that educate workers on local laws and protect the rights of miners.

Our efforts around conflict minerals are illustrative of our commitment to forging sustainable solutions to complex challenges deep within our supply chain. In the last 5 years, Apple worked with peers and stakeholders to implement and improve an industry wide standard, drove compliance with the Conflict Free Sourcing Program or equivalent third party audit programs, and expanded traceability to the mine site. As of November 2015, over 95% of our reported smelters are compliant or participating in a third party audit verifying their conflict-free sourcing practices. And we will not stop until we reach our goal of 100%.

Apple goes beyond what is legally required to drive further change in the DRC and neighboring countries. We provide significant funding and strategic guidance to several programs that are increasing the number of registered miners operating in, and selling their materials through, conflict-free channels, providing educational and health care support to mining communities, developing best practices for small scale miners to improve their productivity and health & safety, and improving methods for tracking and trading materials from the mine to the smelter.

Though it would be a simpler solution to stop our suppliers from sourcing from countries where challenges exist such as the DRC, doing so goes against our core value of leaving the world better than we found it.

We are currently evaluating dozens of different materials, including cobalt, in order to identify labor and environmental risks as well as opportunities for Apple to bring about effective, scalable and sustainable change. As we gain a better understanding of the challenges associated with cobalt we believe our work in the African Great Lakes region and Indonesia will serve as important guides for creating lasting solutions.

We know from experience that we can’t do this alone, and there are no quick fixes to the complex challenges in a global supply chain. But we are committed to being a force for change by advocating for and supporting positive government action and partnering with companies and other stakeholders such as Amnesty International working to make a difference. We have made significant progress, though we know our work is never done and will not stop until every person in our supply chain is treated with the respect and dignity they deserve.

Update: Sony provided TechCrunch with the following statement:

The Sony Group established the “Sony Supplier Code of Conduct” in June 2005 with the expectation of every supplier agreeing and adhering to the policies of the Sony Group in complying with all applicable laws, work ethics, labor conditions, and respect for human rights, environmental conservation and health & safety. Sony has requested its suppliers fully comprehend and comply with this “Sony Supplier Code of Conduct”. As such Sony has a strong commitment to ethical business conduct and we have a stringent policy and management system to minimize the risk of child labor throughout our supply chain.

With respect to cobalt supply chain and human rights issues reported in the Amnesty report, we take this issue seriously and conducted due investigation. So far, we have not found obvious results that our products contain the cobalt originated from Katanga in the DRC.